전기투석공정을 이용한 질산성 질소 분리

고재언,이정문,최태승,심왕근 한국환경기술학회 2022 한국환경기술학회지 Vol.23 No.2

In this study, we evaluate the separation performance of nitrate from water in a recycling batch type electrodialysis (ED) process. In particular, the influences of several operating parameters including the applied current densities and the concentrate concentrations on the ED process performance such as concentrate and dilute concentration profiles, % separation, and energy consumption, were experimentally and theoretically investigated. The two dimensional (2D) batch type ED model based on the extended Nernst-Planck transport theory was used to systematically understand the mass transfer in the ion exchange membrane and the influence of operating conditions on the separation performance. Our results show that the 2D model including the water transport across the membrane is useful to validate the separation of nitrate in different experimental conditions and the concentration behaviors in the concentrate and dilute channels. In addition, the separation performance of nitrate is substantially dependent on the applied current compared to concentrated inlet concentrations.

Electrohydrodynamic Analysis of Dielectric Guide Flow Due to Surface Charge Density Effects in Breakdown Region

이호영,강인만,이세희 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.2

A fully coupled finite element analysis (FEA) technique was developed for analyzing the discharge phenomena and dielectric liquid flow while considering surface charge density effects in dielectric flow guidance. In addition, the simulated speed of surface charge propagation was compared and verified with the experimental results shown in the literature. Recently, electrohydrodynamics (EHD) techniques have been widely applied to enhance the cooling performance of electromagnetic systems by utilizing gaseous or liquid media. The main advantage of EHD techniques is the non-contact and low-noise nature of smart control using an electric field. In some cases, flow can be achieved using only a main electric field source. The driving sources in EHD flow are ionization in the breakdown region and ionic dissociation in the sub-breakdown region. Dielectric guidance can be used to enhance the speed of discharge propagation and fluidic flow along the direction of the electric field. To analyze this EHD phenomenon, in this study, the fully coupled FEA was composed of Poisson’s equation for an electric field, charge continuity equations in the form of the Nernst–Planck equation for ions, and the Navier-Stokes equation for an incompressible fluidic flow. To develop a generalized numerical technique for various EHD phenomena that considers fluidic flow effects including dielectric flow guidance, we examined the surface charge accumulation on a dielectric surface and ionization, dissociation, and recombination effects.

Electrohydrodynamic Analysis of Dielectric Guide Flow Due to Surface Charge Density Effects in Breakdown Region

Ho-Young Lee,In Man Kang,Se-Hee Lee 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.2

A fully coupled finite element analysis (FEA) technique was developed for analyzing the discharge phenomena and dielectric liquid flow while considering surface charge density effects in dielectric flow guidance. In addition, the simulated speed of surface charge propagation was compared and verified with the experimental results shown in the literature. Recently, electrohydrodynamics (EHD) techniques have been widely applied to enhance the cooling performance of electromagnetic systems by utilizing gaseous or liquid media. The main advantage of EHD techniques is the non-contact and low-noise nature of smart control using an electric field. In some cases, flow can be achieved using only a main electric field source. The driving sources in EHD flow are ionization in the breakdown region and ionic dissociation in the sub-breakdown region. Dielectric guidance can be used to enhance the speed of discharge propagation and fluidic flow along the direction of the electric field. To analyze this EHD phenomenon, in this study, the fully coupled FEA was composed of Poisson’s equation for an electric field, charge continuity equations in the form of the Nernst?Planck equation for ions, and the Navier-Stokes equation for an incompressible fluidic flow. To develop a generalized numerical technique for various EHD phenomena that considers fluidic flow effects including dielectric flow guidance, we examined the surface charge accumulation on a dielectric surface and ionization, dissociation, and recombination effects.

Electrohydrodynamic Analysis of Dielectric Guide Flow Due to Surface Charge Density Effects in Breakdown Region

Lee, Ho-Young,Kang, In Man,Lee, Se-Hee The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.2

A fully coupled finite element analysis (FEA) technique was developed for analyzing the discharge phenomena and dielectric liquid flow while considering surface charge density effects in dielectric flow guidance. In addition, the simulated speed of surface charge propagation was compared and verified with the experimental results shown in the literature. Recently, electrohydrodynamics (EHD) techniques have been widely applied to enhance the cooling performance of electromagnetic systems by utilizing gaseous or liquid media. The main advantage of EHD techniques is the non-contact and low-noise nature of smart control using an electric field. In some cases, flow can be achieved using only a main electric field source. The driving sources in EHD flow are ionization in the breakdown region and ionic dissociation in the sub-breakdown region. Dielectric guidance can be used to enhance the speed of discharge propagation and fluidic flow along the direction of the electric field. To analyze this EHD phenomenon, in this study, the fully coupled FEA was composed of Poisson's equation for an electric field, charge continuity equations in the form of the Nernst-Planck equation for ions, and the Navier-Stokes equation for an incompressible fluidic flow. To develop a generalized numerical technique for various EHD phenomena that considers fluidic flow effects including dielectric flow guidance, we examined the surface charge accumulation on a dielectric surface and ionization, dissociation, and recombination effects.

Temperature effect on multi-ionic species diffusion in saturated concrete

Nattapong Damrongwiriyanupap,Linyuan Li,Suchart Limkatanyu,Yunping Xi 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.2

This study presents the mathematical model for predicting chloride penetration into saturated concrete under non-isothermal condition. The model considers not only diffusion mechanism but also migration process of chloride ions and other chemical species in concrete pore solution such as sodium, potassium, and hydroxyl ions. The coupled multi-ionic transport in concrete is described by the Nernst-Planck equation associated with electro-neutrality condition. The coupling parameter taken into account the effect of temperature on ion diffusion obtained from available test data is proposed and explicitly incorporated in the governing equations. The coupled transport equations are solved using the finite element method. The numerical results are validated with available experimental data and the comparison shows a good agreement.

Coupled diffusion of multi-component chemicals in nonsaturated concrete

Nattapong Damrongwiriyanupap,Linyuan Li,Yunping Xi 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.3

A comprehensive simulation model for the transport process of fully coupled moisture and multispecies in non-saturated concrete structures is proposed. The governing equations of moisture and ion diffusion are formulated based on Fick’s law and the Nernst-Planck equation, respectively. The governing equations are modified by explicitly including the coupling terms corresponding to the coupled mechanisms. The ionic interaction-induced electrostatic potential is described by electroneutrality condition. The model takes into account the two-way coupled effect of moisture diffusion and ion transport in concrete. The coupling parameters are evaluated based on the available experimental data and incorporated in the governing equations. Differing from previous researches, the material parameters related to moisture diffusion and ion transport in concrete are considered not to be constant numbers and characterized by the material models that account for the concrete mix design parameters and age of concrete. Then, the material models are included in the numerical analysis and the governing equations are solved by using finite element method. The numerical results obtained from the present model agree very well with available test data. Thus, the model can predict satisfactorily the ingress of deicing salts into non-saturated concrete.

Electrohydrodynamic instability of dielectric liquid between concentric circular cylinders subjected to unipolar charge injection

페르난데스,Heon-Deok Lee,박승호,서용권 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.2

In this paper, we demonstrate instability of dielectric liquid subjected to unipolar charge injection from a pair of cylindrical electrodes at high Scmidt and high Peclet numbers. The transport of charge density in the annulus is governed by the Nernst-Planck equation and the electric potential by the Poisson equation. The fluid flow is governed by the Navier-Stokes equation together with the continuity equation. The base solutions composed of the one-dimensional conduction state are obtained numerically and the temporal growth of their perturbations is determined from the normal-mode instability analysis by using numerical simulations. The critical values of the parameter for the onset of 2D convective motion are obtained and compared well with the results of full-2D calculation. At high injection, the system tends to be more unstable for the inner injection case and more stable for the outer injection case, as the radius of the inner cylinder is decreased; this trend is however reversed at low injection. It turns out that the critical angular wave number obtained from the flat-plate case well predicts the one for an annulus for a wide range of the inner cylinder’s radius.

Evaluation of thermodynamic and kinetic parameters for conducting nanocomposite polypyrrole zirconium titanium phosphate

Asif Ali Khan,Leena Paquiza 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

The kinetics and mechanism for the ion-exchange processes like Mg(II)–H(I), Ca(II)–H(I), Sr(II)–H(I),Ba(II)–H(I), Ni(II)–H(I), Cu(II)–H(I), Mn(II)–H(I) and Zn(II)–H(I) at different temperatures usingapproximated Nernst–Plank equation under the particle diffusion controlled phenomenon werestudied for the polypyrrole zirconiumtitanium phosphate nanocomposite cation exchanger. TEM provesthe formation of the nanocomposite cation exchanger. Some physical parameters, i.e. fractionalattainment of equilibrium UðtÞ, self-diffusion coefficients (D0), energy of activation (Ea) and entropy ofactivation (DS8) have been estimated. These results are useful for predicting the ion exchange processoccurring on the surface of this cation-exchanger.

Global axisymmetric solutions to the 3D Navier--Stokes--Poisson--Nernst--Planck system in the exterior of a cylinder

Jihong Zhao 대한수학회 2021 대한수학회보 Vol.58 No.3

In this paper we prove global existence and uniqueness of axisymmetric strong solutions for the three dimensional electro-hydrodyna\-mic model based on the coupled Navier--Stokes--Poisson--Nernst--Planck system in the exterior of a cylinder. The key ingredient is that we use the axisymmetry of functions to derive the $L^{p}$ interpolation inequalities, which allows us to establish all kinds of a priori estimates for the velocity field and charged particles via several cancellation laws.

Numerical Particle-Scale Study of Swelling Pressure in Clays

David W. Smith,Guillermo A. Narsilio,Peter Pivonka 대한토목학회 2009 KSCE Journal of Civil Engineering Vol.13 No.4

The particle level responses to different external loadings of a montmorillonitic clay soil are investigated numerically. The soil is saturated by a solution of monovalent counterions, of varying concentrations. We use finite element micromechanical models (based on the Poisson-Nernst-Planck equations) to estimate counterion and electrical potential distributions around individual clay particles at various distances from one another, since analytical solutions are not possible for these complex arrangements of particles. Disjoining pressures are then estimated using the Van’t Hoff relation and Maxwell stress tensor. As the distance between the clay particles decreases and double-layers overlap, the concentration of counterions in the micropores between clay particles increases. This increase lowers the chemical potential of the pore fluid and creates a chemical potential gradient in the solvent that generates the so-called “disjoining” or “osmotic” pressure. Because of this disjoining pressure, it is clear that particles need not contact one another in order to carry an “effective stress”. This work may lead towards theoretical predictions of the macroscopic load deformation response of montmorillonitic soils based on micro-electro-chemo-mechanical modelling of particles. The particle level responses to different external loadings of a montmorillonitic clay soil are investigated numerically. The soil is saturated by a solution of monovalent counterions, of varying concentrations. We use finite element micromechanical models (based on the Poisson-Nernst-Planck equations) to estimate counterion and electrical potential distributions around individual clay particles at various distances from one another, since analytical solutions are not possible for these complex arrangements of particles. Disjoining pressures are then estimated using the Van’t Hoff relation and Maxwell stress tensor. As the distance between the clay particles decreases and double-layers overlap, the concentration of counterions in the micropores between clay particles increases. This increase lowers the chemical potential of the pore fluid and creates a chemical potential gradient in the solvent that generates the so-called “disjoining” or “osmotic” pressure. Because of this disjoining pressure, it is clear that particles need not contact one another in order to carry an “effective stress”. This work may lead towards theoretical predictions of the macroscopic load deformation response of montmorillonitic soils based on micro-electro-chemo-mechanical modelling of particles.